Digitizer systems that include capacitive based sensors are used as input devices for a variety of Human Interface Devices (HIDs) and for a variety of different applications. A touch-screen is one type of digitizer system that is integrated with a Flat Panel Display (FPD). Touch-screens are used for operating portable devices, such as laptop computers, tablet computers, MP3 players, smart phones and other devices.
Digitizer systems track free style input provided with a finger and/or stylus. A mutual capacitive sensor is one type of capacitive sensor for a digitizer system. Mutual capacitive sensors typically include a matrix formed with parallel conductive material arranged in rows and columns with a capacitive connection created around overlap and/or junction areas formed between rows and columns Bringing a finger or conductive object close to the surface of the sensor changes the local electrostatic field and reduces the mutual capacitance between junction areas in the vicinity of the finger or conductive stylus. The capacitance change at junction points on the grid can be detected to determine location of the finger or conductive object on the capacitive sensor. The capacitance change is determined by applying a signal along one axis of the matrix and measuring the signal in the other axis. Mutual capacitance allows multi-touch operation where multiple fingers, palms or styli can be tracked at the same time.